Removal of color from plastic materials



FIP8309 XR 1 ,1.e7 ICAIILLOGLFIDUm,

Patented July 28, 15925..

'ari

Heierence JOHN MORRIS WEISS, OF NEW YORK, N. Y.

.nnmovan or canon more rnasrro MATERIALS.

n Drawing. Application filed January To all whom it may concern.-

Be it'knoivn that 1, JOHN Mourns Verse, a citizen of the United States, and'residmg in the city and county of New York and ion, some of ,which are later specifically mentioned.

Plastics come into trade in various forms, many of which are colored by soluble dyestuffs to give various pleasing or artistic re,

- suits or to imitate the appearance of certain naturalurticles. ,"lhus, celluloid comes on the market in sheets of various gradesand colors, some clear, some clear amber color and quite avaricty of vmixed colors of which one ofthe commonest is imitation tortoise shell. In the manufacture of articles such as imitation tortoise shell eye-glass frames,

which are cut from solid strips of celluloid,

the scrap cuttings may amount to over 80% .of the'raw materials used. This scrap can be formed again into sheiets by softening with a suitable solvent such as acetone, ethyl acetate, etc, milling, pressing and, in general, proceeding as in thc'olriginal manufacture of the sheeted prodiicth The scrap, however, contains dyes to color it and as in the case of eye-glass frames,- to give them a tortoise shell effect. These: dyes are not altered materially in the above treatment and the recovered scrap is therefore only useful for production of black or verydark articles. Attempts have been made to employ mineral bleaching agents such as chlorine but these have proved impractical because of injury to the nitrocellulose or camphor constitutents of the celluloid. itself, producing nv composition in irrior to that manulzwtured directly from the raw materials;

I have found that if peroxides of organic acids such as benzoyl peroxide, phthalyl peroxide, fnnmryl peroxide. plitlrulic acid peroxide, etc., are used as a hie-aching agent 2, 192a Serial No. 634,088.

in the recovery process, that the bulk of the color is removed without damage to the celluloid substance and the resulting product can again-be used for the production of light colored, transparent material or by the suit able addition of colored material, for the production of imitation tortoise shell stock.

lVithout limiting myself thereby I state Ullwwn 'that the formulae'bf the compounds referred to has been considered to be as follows:

Benzoyl peroxide CaHsCOO CO-O Phtlmlvl peroxide CoH4 l Fnmsn'yl peroxide CH-CO-O CHCDf) ooH' ihtliulu; ZiUld peroxide CuHi Z 5 coonr The peroxides have, been prepared by treat- 'ing the acid chlorides with sodium perdxide under suitable conditions.

As a specific example of my invention, the following is cited, it being understood that 1 do not limit myself to the specific proportions stated andthe specific peroxide given is for illustrative purposes only as other peroxides may be used Without departing from thespirit and scope of theiuvent ion. i

To one hundred pounds of scrap are added fifty pounds (if-ethyl acetate in which threequarters pound 'of a 60% phthalyl peroxide is dissolved. The mass is'allowed to stand until the ethyl acetate is absorbed, the Whole forming a soft plastic mass. This process distributes the peroxide through the mass of celluloid and the bleaching occurs gradually, being hastened somewhat by warming or the addition of a traceof alkali. Twenty-four hours standing in the cold is usually sutlicient to complete the process; at 100 F. ten to fifteen minutes suffice. The mass is then milled on rolls, this and the subsequent operations being carried out just as in-the original manufacture of the celluloid. The finished product is colorless to pale yellow and suitable for themanufacture of light colored transparent articles.

- The amount of solvent, the type of solvent and the amount of peroxide are all subject to wide variation. The amount of peroxide will naturally vary with the kind and strength of the color to be removed. The process is not applicable where the color is due to mineral pigments such as lampblack but is generally applicable with organic coloring matters, particularly the oil-soluble dyes. Any peroxide of an organic acid can be used, provided the oxygen is loosely bound so as to exert bleaching action. The one to be selected depends on commercial availability and cost.

The process is applicable to ordinary celluloid, to plastics of the same type with a cellulose acetate base, to viscose, synthetic and natural resins, and, in general, products of the plastic type which have been colored with colors or dyes which color is capable of being discharged by oxidizing agents.

Having thus described my invention, I

.claim:

l. The removal of organic color from orgame plastics comprising the addition of a peroxide of an organic acid.

comprises the addition of phthalyl peroxide to the scrap. I

6. The improvement in the recovery of celluloid scrap containing organic color which comprises the addition of phthalyl peroxide dissolved in ethyl acetate to the scrap.

7. The improvement in the recovery ofcelluloid scrap containing organic color whichcomprises the addition of a peroxide of an organic acid to a mixture of the scrap with a celluloid solvent.

8. The improvement in the recovery of colluloid scrap containing organic color which comprises the addition of phthalyl peroxide to a mixture of the scrap with a celluloid solvent.

9. The improvement in the recovery of celluloid scrap containing organic color which comprises the addition of phthalyl peroxide to a mixture of the scrap with ethyl acetate.

10. The improvement in the recovery of celluloid scrap containing organic color which comprises the addition of a peroxide of anorganic acid to a mixture of the scrap with ethyl acetate.

11. The removal of organic color from organic plastics comprising the addition of an organic peroxide to a mixture of the plastic and a celluloid solvent.

12. The removal of organic color from (H' ganic plastics comprising the addition of phthalyl peroxide to a mixture of they plastic and a celluloid solvent.

In testimony whereof, I hcrchy allix my signature.

JOHN MORRIS \V l l SS. 

